How do you share data between view controllers and other objects in Swift?

Question

Say I have multiple view controllers in my Swift app and I want to be able to pass data between them. If I\'m several levels down in a view controller stack, how do I pass d

Answer 1

It depends when you want to get data.

If you want to get data whenever you want, can use a singleton pattern. The pattern class is active during the app runtime. Here is an example of the singleton pattern.

class AppSession: NSObject {

    static let shared = SessionManager()
    var username = "Duncan"
}

class ViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()

        print(AppSession.shared.username)
    }
}

If you want to get data after any action, can use NotificationCenter.

extension Notification.Name {
    static let loggedOut = Notification.Name("loggedOut")
}

@IBAction func logoutAction(_ sender: Any) {
    NotificationCenter.default.post(name: .loggedOut, object: nil)
}

NotificationCenter.default.addObserver(forName: .loggedOut, object: nil, queue: OperationQueue.main) { (notify) in
    print("User logged out")
}